算术表达式求值

#include<stdlib.h>
#include<stdio.h>
#define stack_init_size1 40
#define stack_init_size2 20
#define stackincrement1 40
#define stackincrement2 20
typedef struct{
    int *base;
    int *top;
    int stacksize;
}s_stack;
typedef struct{
    char *base;
    char *top;
    int stacksize;
}f_stack;

static char youxian[7][7]=
    { // ‘+’ ‘-‘ ‘*’ ‘/’ ‘(‘ ‘)’ ‘#’
        {‘>’,’>’,'<‘,'<‘,'<‘,’>’,’>’},
        {‘>’,’>’,'<‘,'<‘,'<‘,’>’,’>’},
        {‘>’,’>’,’>’,’>’,'<‘,’>’,’>’},
        {‘>’,’>’,’>’,’>’,'<‘,’>’,’>’},
        {‘<‘,'<‘,'<‘,'<‘,'<‘,’=’,’>’},
        {‘>’,’>’,’>’,’>’,’>’,’>’,’>’},
        {‘<‘,'<‘,'<‘,'<‘,'<‘,’>’,’=’}
    };

int in(char c)
{
    switch(c)
    {
    case ‘+’:
return 0;
    case ‘-‘:
return 1;
    case ‘*’:
return 2;
    case ‘/’:
return 3;
    case ‘(‘:
return 4;
    case ‘)’:
return 5;
    case ‘#’:return 6;
    default:return 9;
    }

}

void s_push(s_stack *s,int e)
{

     if(s->top-s->base>=s->stacksize)
     {
         s->base=(int
*)realloc(s->base,(s->stacksize+stackincrement1)*sizeof(int));
         if(!s->base) exit(0);
         s->top=s->base+s->stacksize;
         s->stacksize+=stackincrement1;
     }
    *s->top=e; s->top++;
    /*printf(“the s_stack has the
data:%dn”,*(s->top-1));*/
}
void  f_push(f_stack *f,char e)
{
     if(f->top-f->base>=f->stacksize)
     {
         f->base=(char
*)realloc(f->base,(f->stacksize+stackincrement2)*sizeof(char));
         if(!f->base) exit (0);
         f->top=f->base+f->stacksize;
         f->stacksize+=stackincrement2;
     }
     *f->top=e;f->top++;
    /*
printf(“the f_stack has the sign:%cn”,*(f->top-1));*/
}

int s_gettop(s_stack *s)
{
    s->top–;
    return *s->top;
}

char f_gettop(f_stack *f)
{
    f->top–;
    return *f->top;
}

char panduan(f_stack *f,char c)
{
    int m,n;
    char w;
    m=in(c);
    w=*(f->top-1);
    n=in(w);
    return youxian[n][m];
}

int yunsuan(int p,char r,int q)
{
        switch(r)
    {
        case ‘+’:
return q+p;
        case ‘-‘:
return q-p;
        case ‘*’:
return q*p;
        case ‘/’:
return q/p;
    }
}
int main()

{
    int h=0,jieguo,wrong;
    char c;
    s_stack s;
    f_stack f;
    s.base=(int*)malloc(stack_init_size1*sizeof(int));
    if(!s.base) return 0;
    s.top=s.base;
    s.stacksize=stack_init_size1;

    f.base=(char*)malloc(stack_init_size2*sizeof(char));
    if(!f.base) return 0;
    f.top=f.base;
    f.stacksize=stack_init_size2;
    *f.top=’#’;f.top++;

    printf(“please press the shizi end by
enter!n”);
    c=getchar();
    while(c!=’n’)
    {   int t;
        int p,q;
        char r;
        if(in(c)==9)
        {   if(h>0)
         {
            t=s_gettop(&s);
            s_push(&s,t*10+c-48);
         }
         else
             s_push(&s,c-48);
         h++;
         c=getchar();
        }
        else
        switch(panduan(&f,c))
        {
          case ‘<‘:
               f_push(&f,c);c=getchar();h=0;break;
          case ‘=’:
               f.top–;
               f.stacksize–;
               c=getchar();h=0;break;
          case ‘>’:
               p=s_gettop(&s);
               q=s_gettop(&s);
               r=f_gettop(&f);
             if(r==’/’&&p==0)
               {wrong=1;break;}
             else
               { jieguo=yunsuan(p,r,q);
                 s_push(&s,jieguo);h=0;break;
               }
        }
    }
    while((c==’n’)&&(*(f.top-1)!=’#’))
    {
        int p,q;
        char r;
        p=s_gettop(&s);
        q=s_gettop(&s);
        r=f_gettop(&f);
    if(r==’/’&&p==0)
        {wrong=1;break;}
    else
        jieguo=yunsuan(p,r,q);
        s_push(&s,jieguo);
    }
    if(wrong==1)
        printf(“It is wrong!n”);
    else
        printf(“the answer is %dn”,s_gettop(&s));
}

发表评论

电子邮件地址不会被公开。 必填项已用*标注